Commercial applications of cyanuric acid require that the acid contain as low as possible amounts of the impurities, ammelide and ammeline. Cyanuric acid produced according to the process disclosed in the above-mentioned Netherlands Patent Application may contain commercially unacceptable amounts of the impurities, ammelide and ammeline. It is possible to remove these impurities from cyanuric acid by treatment with a strongly acid aqueous solution to hydrolyze the ammelide and ammeline into cyanuric acid. However, such a hydrolysis step is expensive.
It is therefore an objective of the present invention to prepare cyanuric acid by heating a solution of urea and/or biuret in a polar organic solvent while reducing the amounts of the co-produced ammelide and ammeline.